In a usual single-plate solid-state image device, since photodiodes are provided on substantially the same plane as a charge transfer path, there is involved a defect that following high integration of pixels, the photodiodes are hardly waveguided. For that reason, though incident light is condensed into the photodiodes by a microlens or the like, its condensation efficiency is not satisfactory. Furthermore, the condensation efficiency may possibly differ depending upon a light incident angle, resulting in a problem such as shading. In addition, in forming a microlens, there are brought an increase in the number of processes and an increase in costs. In order to obtain a color-separated signal, a color filter is needed, and this brings an increase in the number of processes and an increase in costs, too.
As an imaging device with a high aperture factor, there is proposed an imaging device in which a photoelectric conversion device having an a-Si (amorphous silicon) photoelectric conversion layer interposed between a pair of electrodes is provided on a silicon substrate having a signal read-out circuit formed thereon (see JP-A-8-88341). However, in the a-Si, it is difficult to disperse light in a visible light region with good color separation and a color filter is needed, leading to an increase in costs. Also, for the purpose of desiring sufficient optical absorption, a thickness of several μm of the photoelectric conversion layer is needed, and manufacturing costs by a high-frequency glow discharge decomposition method are high.